Effect of cyclic strain on cardiomyogenic differentiation of rat bone marrow derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a potential source of material for the generation of tissue-engineered cardiac grafts because of their ability to transdifferentiate into cardiomyocytes after chemical treatments or co-culture with cardiomyocytes. Cardiomyocytes in the body are subjected to cyclic strain induced by the rhythmic heart beating. Whether cyclic strain could regulate rat bone marrow derived MSC (rBMSC) differentiation into cardiomyocyte-like lineage was investigated in this study. A stretching device was used to generate the cyclic strain for rBMSCs. Cardiomyogenic differentiation was evaluated using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR), immunocytochemistry and western-blotting. The results demonstrated that appropriate cyclic strain treatment alone could induce cardiomyogenic differentiation of rBMSCs, as confirmed by the expression of cardiomyocyte-related markers at both mRNA and protein levels. Furthermore, rBMSCs exposed to the strain stimulation expressed cardiomyocyte-related markers at a higher level than the shear stimulation. In addition, when rBMSCs were exposed to both strain and 5-azacytidine (5-aza), expression levels of cardiomyocyte-related markers significantly increased to a degree suggestive of a synergistic interaction. These results suggest that cyclic strain is an important mechanical stimulus affecting the cardiomyogenic differentiation of rBMSCs. This provides a new avenue for mechanistic studies of stem cell differentiation and a new approach to obtain more committed differentiated cells.